Perfil farmacológico de compostos com aplicações como agentes antineoplásicos, antimicrobianos e contra doenças neurodegenerativas

O presente trabalho consistiu na síntese e estudo do perfil farmacológico de três classes de compostos - tiossemicarbazonas, bis(fenilhidrazonas) e clioquinol - e seus complexos metálicos. A potencial capacidade de tiossemicarbazonas selecionadas de atuarem como agentes quelantes para uso na remoção de metais de cérebros de pacientes portadores de doenças neurodegenerativas foi investigada. Os efeitos citotóxicos de tiossemicarbazonas, bis(fenilhidrazonas), clioquinol e seus complexos metálicos foram avaliados frente a células de leucemia e de tumores sólidos, e foi estudada a ação antimicrobiana dos compostos em culturas de bactérias e fungos. Uma série de tiossemicarbazonas com caráter bidentado foi planejada, as quais em princípio poderiam atuar pela complexação e remoção de metais associados a doenças neurodegenerativas. Doze tiossemicarbazonas derivadas de acetofenona e benzofenona N(3)-substituídas foram obtidas, sendo oito delas inéditas. Quatro estruturas cristalográficas foram determinadas. A atividade antimicrobiana contra cepas de Staphylococus aureus, Pseudomonas aeruginosa e Candida albicans, e a atividade citotóxica desses compostos frente a células leucêmicas (HL-60, Jurkat e K562), de tumor mamário (MCF-7) e de glioblastomas (U-87 e T-98) humanos foram avaliadas, porém, todos os compostos revelaram-se pouco ativos. cetofenona-N(3)-meta-toluil tiossemicarbazona mostrou baixa toxicidade oral in vivo. A capacidade quelante, a baixa toxidez frente a diferentes sistemas biológicos e o valor de logP na faixa adequada para chegar ao cérebro sugerem que esse composto em particular e a família de tiossemicarbazonas estudadas poderiam constituir novos candidatos a protótipos de fármacos para o tratamento de pacientes com doenças neurodegenerativas. Foram obtidos oito complexos de zinco(II) com as tiossemicarbazonas derivadas de acetofenona e benzofenona N(3)-meta- substituídas. Duas estruturas cristalográficas foram determinadas. Todos os complexos foram inativos contra o crescimento de bactérias S. aureus e P. aeruginosa. Complexos de ouro(I, III) e de platina(II, IV) foram preparados com 2-formilpiridina-, 2- acetilpiridina- e 2-benzoilpiridina- N(4)-toluil- tiossemicarbazonas. Os efeitos citotóxicos dos compostos foram investigados frente a células de glioblastomas humanos U-87 e T-98 e células sadias de fibroblastos de pulmão de feto humano (MRC-5). As tiossemicarbazonas livres mostraram-se altamente citotóxicas frente a todas as linhagens celulares. Em alguns casos, a coordenação aos metais melhorou o efeito citotóxico. Alguns compostos revelaram-se mais ativos que cisplatina e auranofina. Os complexos de ouro(I, III) foram mais ativos que seus análogos de platina(II, IV) contra as células U-87 e T-98. Por sua vez, a maioria dos complexos de platina(IV) foi mais ativa que seus análogos de platina(II) contra as duas linhagens de células. 2-Acetilpiridina-N(4)-meta-toluil tiossemicarbazona, seus complexos de ouro(III) e de platina(II, IV) foram avaliados quanto à capacidade em inibir a atividade da enzima tiorredoxina redutase (TrxR). Apenas o complexo de ouro(III) inibiu significativamente a atividade da TrxR. Os mesmos compostos foram avaliados quanto à interação com ADN plasmidial. Apenas os complexos de platina(II, IV) interagiram significativamente com o ADN. Esses resultados sugerem que os modos de ação citotóxica dos complexos de platina podem ter como alvo principal o ADN, enquanto que os complexos de ouro agem majoritariamente pela inibição da enzima TrxR. Complexos de bismuto(III) e antimônio(III) foram preparados com ,6-diacetilpiridina bis(fenilhidrazona) e seus derivados. Duas estruturas cristalográficas foram determinadas. As atividades antimicrobianas dos compostos foram avaliadas contra o crescimento de S. aureus, Staphylococus epidermidis, Enterococcus faecalis, P. aeruginosa e C. albicans. As bis(fenilhidrazonas) não foram ativas contra o crescimento dos microorganismos. Em geral, a coordenação a bismuto(III) e antimônio(III) fez aumentar a atividade antifúngica. Os complexos de bismuto(III) foram mais potentes como antimicrobianos do que seus análogos de antimônio(III). A citotoxicidade das bis(fenilhidrazonas) e seus complexos de bismuto(III) e antimônio(III) foi avaliada frente as células HL-60, MCF-7, HCT-116 (carcinoma colo retal) e células mononucleares de sangue periférico (PBMC). Em geral, as bis(fenilhidrazonas) foram pouco ativas. A coordenação ao bismuto(III) foi uma boa estratégia para aumentar o efeito citotóxico das bis(fenilhidrazonas) contra todas as linhagens de células. Os complexos de bismuto(III) foram mais ativos que seus análogos de antimônio(III) e, na maioria dos casos, mais ativos que a cisplatina. Em geral, os complexos de bismuto(III) exibiram bons valores de índices terapêuticos. Para as bis(fenilhidrazonas) e seus complexos de bismuto(III), a morte por apoptose não é o único modo de ação citotóxica. A atividade das bis(fenilhidrazonas) e seus complexos de antimônio(III) foi avaliada contra Leishmania (L.) amazonensis. Os compostos apresentaram atividade contra L. amazonensis. A coordenação ao antimônio (III) não fez melhorar a atividade. Foram preparados complexos de clioquinol com platina(II, IV). A estrutura cristalográfica do complexo de platina(II) foi determinada. A atividade citotóxica foi avaliada frente a células Jurkat, HL60, MCF-7 e HCT-116 e todos os compostos revelaram-se pouco ativos contra todas as células. Os complexos foram aproximadamente quatro vezes mais ativos que o clioquinol e pouco mais ativos que a cisplatina contra as células HL-60. Dois complexos de estanho(IV) foram obtidos com o clioquinol. A atividade antimicrobiana dos compostos foi avaliada contra S. aureus, P. aeruginosa e C. albicans. A coordenação do clioquinol ao estanho(IV) fez aumentar a atividade antifúngica, mas não melhorou a atividade antibacteriana. Os complexos foram aproximadamente cem vezes mais ativos como antifúngicos do que o fluconazol. A ação antifúngica do clioquinol e dos complexos de estanho(IV) foi avaliada contra quatro espécies de Candida spp. (C. albicans, Candida krusei, Candida glabrata e Candida parapsilosis). Em geral, a coordenação a estanho(IV) melhorou a atividade do clioquinol contra a maioria das espécies.The present work involved the syntheses and a study on the pharmacological profile of three classes of compounds: thiosemicarbazones, bis(benzoylhydrazones) and clioquinol, as wellas their metal complexes. The potential ability of selected thiosemicarbazones to function as chelating agents for the treatment of neurodegenerative disorders was investigated. The cytotoxiceffects of thiosemicarbazones, bis(benzoylhydrazones), clioquinol and some of their metal complexes was studied against leukemia and solid human tumor cell lineages. The antimicrobial effects of the bis(benzoylhydrazones), clioquinol and their metal complexes was also investigated. A series of bidentate thiosemicarbazones was designed which could in principle act by complexing and removing metal ions associated to neurodegenerative diseases. Twelve N(3)-meta-substituted acetophenone- and benzophenone-derived thiosemicarbazones were obtained. Eight among these thiosemicarbazones were synthesized for the first time in the present work. Four crystal structures were determined. All thiosemicarbazones proved to be inactive against the growth of Staphylococus aureus, Pseudomonas aeruginosa and Candida albicans, and showedvery low cytotoxic activities against HL-60, Jurkat and K562 leukemia cells and against MCF-7 (breast cancer) and U-87 and T-98 glioma cell lineages. Acetophenone-N(3)-meta-tolyl thiosemicarbazone showed low oral acute toxicity in vivo. The chelating ability of this compound,its low oral toxicity and low pharmacological effects, together with its logP which favors its passage through the cell membranes suggest that the compound could be interesting as a new drug candidate prototype to treat neurodegenerative disorders. Eight zinc(II) complexes were obtained with the acetophenone- and bezophenone-derived thiosemicarbazones. Two crystal structures were determined. All complexes proved to be inactiveagainst the growth of S. aureus and P. aeruginosa bacteria.Gold (I, III) and platinum(II, IV) complexes were obtained with 2-formylpyridine, 2- acetylpyridine- and 2-benzoylpyridine- N(4)-tolyl thiosemicarbazone. The cytotoxicities of the compounds were investigated against U-87 and T-98 human glioma cells and against MRC-5 human fetus lung fibroblast cells. The thiosemicarbazones proved to be cytotoxic to all cells. Upon coordination the cytotoxic effect increased in some cases. Some of the studied compounds showed higher cytotoxic activity than cisplatin and auranofin. The gold(I, III) complexes revealed to be more active than the corresponding platinum(II, IV) complexes against U-87 and T-98 cells. The platinum(IV) complexes were more cytotoxic than the corresponding platinum(II)counterparts against U-87 and T-98 glioma cell lineages.2-Acetylpyridine-N(4)-meta-tolyl thiosemicarbazone and its gold(III) and platinum(II, IV) complexes were evaluated for their ability to inhibit the activity of thioredoxin reductase (TrxR) enzyme. Only the gold(III) complex significantly inhibit TrxRs activity. The same compounds were evaluated for their ability to interact with plasmid DNA. Only the platinum(II, IV)complexes strongly interacted with DNA. The foregoing results suggest that the mode of cytototoxic action of the platinum compounds involves DNA as a target while the cytotoxic effect of the gold compounds involves inhibition of TrxR. Bismuth(III) and antimony(III) complexes were obtained with 2,6-diacetylpyridine bis(benzoylhydrazone) and its derivatives. Two crystal structures were determined. The antimicrobial activities of the compounds were evaluated against the growth of S. aureus,Staphylococus epidermidis, Enterococcus faecalis, P. aeruginosa and C. albicans. The bis(benzoylhydrazones) were inactive against all tested microorganisms. Upon coordination to both bismuth(III) and antimony(III) the antifungal activity increased. The bismuth(III) complexesrevealed to be more active as antimicrobials than their antimony(III) counterparts. The bis(benzoylhydrazones) and their bismuth(III) and antimony(III) complexes were assayed as well for their cytotoxic activities against Jurkat and HL-60 leukemia, MCF-7 and HCT-116 (colo-rectal carcinoma) tumor cell lineages and against peripheral blood mononuclear (PBMC) cells. In general the bis(benzoylhydrazones) showed low cytotoxic activity against all cell lines. Coordination to bismutth(III) proved to be an efficient strategy for activityimprovement against all cell lineages. The bismuth(III) complexes were more cytotoxic than the antimony(III) analogs and most of them were more active than cisplatin. In general, the bismuth(III) complexes exhibited good therapeutic indexes. For the bis(benzoylhydrazones) andtheir bismuth(III) complexes apoptosis induction is not the only mode of cytotoxic activity. The bis(benzoylhydrazones) and their antimony(III) complexes were tested for their activity against Leishmania (L.) amazonensis. The activity of 2,6-diacetylpyridine bis(benzoylhydrazones) was demonstrated for the first time in the present work. Coordination didnot affect the anti-leishmanial activity of the bis(hydrazones).Complexes of clioquinol were obtained with platinum(II, IV). The crystal structure of the platinum(II) complex was determined. The citotoxicity was evaluated against Jurkat, HL60, MCF- 7 and HCT-116 cells. Both complexes were fourfold more active than clioquinol and slightlymore active than cisplatin against HL-60 cells. Two organotin(IV) complexes were obtained with clioquinol. The antimicrobial activitiesof clioquinol and its tin(IV) complexes was assayed against S. aureus, P. aeruginosa and C. albicans. Coordination to tin(IV) proved to be a good strategy for improving the antifungal but not the antibacterial activity of clioquinol. The complexes revealed to be 100-fold more active asantifungal agents than fluconazole. The antifungal activity of clioquinol and its organotin complexes was evaluated against four species of Candida spp. (C. albicans, Candida krusei, Candida glabrata and Candida parapsilosis). In general coordination to tin(IV) resulted in higherantifungal activity against most of the Candida species.Combinations of the organotin complexes with fluconazole were assayed against twelve isolates of C. albicans. In many cases the organotin complexes/fluconazole combinations were more potent as antifungals than the clioquinol/fluconazole combination. The present work is an important contribution to Medicinal Inorganic Chemistry sincenew drug candidate prototypes were investigated for the treatment of neurodegenerative disorders, neoplasias and microbial infection